Everyone thinks gravity sucks, but in most of the Universe it blows
Children at school are still taught that gravity is a force of attraction. However, in 1998, astronomers discovered to their immense surprise that the expansion of the Universe is speeding up, and they have attributed this to the repulsive gravity of mysterious ‘dark energy’, invisible stuff filling all of space. Dark energy accounts for more than two-thirds of the mass-energy of the Universe. Nobody knows what it is. In fact our very best theory (quantum theory) predicts an energy for the vacuum of space (dark energy) – that is one followed by 120 zeroes bigger than what is observed. This is the biggest discrepancy between a prediction and an observation in the history of science. Something is wrong!